The "warming hiatus" that has occurred over the last 15 years has been caused in part by small volcanic eruptions. Scientists have long known that volcanoes cool the atmosphere because of the sulfur dioxide that is expelled during eruptions. Droplets of sulfuric acid that form when the gas combines with oxygen in the upper atmosphere can persist for many months, reflecting sunlight away from Earth and lowering temperatures at the surface and in the lower atmosphere. New research further identifies observational climate signals caused by recent volcanic activity.

'The difference between a Miracle and a Fact is exactly the difference between a mermaid and seal. It could not be expressed better.' -- Samuel "Mark Twain" Clemens

But what about the sea temperatures? There doesn't seem to have been any slowdown in the rate at which global sea levels are rising, which would indicate that, as far as sea temperatures go, there has been no "hiatus". Why would a reduction in insolation due to volcanic aerosols slow land warming but not sea warming?

He did say "in part". The cooling effects of large eruptions has been seen in the ocean data. The effect this article is talking about may well have been masked by the accelerated deep ocean warming caused by the circulation change beginning at the same point. That effect caused significant surface cooling. Deep water warmed...